The solid content in the drilling mud has several operational impacts on drilling operation as listed below;
Equivalent Circulating Density (ECD)
– The ECD will be higher if the solid content increases, regardless of whether High Gravity Solid (HGS) or Low Gravity Solid (LGS). As you may know, excessive ECD will lead to formation fracture and a loss circulation issue.
– The filter cake can be thick and sticky, if there are a lot of low gravity solids in the drilling mud. When there is thick mud cake, you will have high potential to get differentially stuck across permeable formations.
Rate of penetration
– High concentration of the solid content will affect the overall rate of penetration. As you know, there are three solid contents added into the system. The first two contents are weighting material and chemicals which we really need them in the drilling fluid. For this part, we cannot reduce their content in the mud because they are essential to for mud properties. The last one is the drill solid that we are able to control by mechanical methods. Therefore, in order to optimum ROP, you need to control the amount of drilled solid in the mud.
– The excessive surge and swab pressures are resulted from the high amount of solid contents in the fluid system.
Ref: Learn about drilling mud at drilling mud